1. Field of the Invention
The present invention relates to wireless communications, and more particularly, to a method and apparatus for supporting a closed subscriber group (CSG) service in a wireless communication system.
2. Related Art
The Third Generation Partnership Project (3GPP) Long Term Evolution (3GPP LTE) which is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) is introduced as 3GPP Release 8. The 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) for the downlink, and single carrier frequency division multiple access (SC-FDMA) for the uplink, and adopts multiple input multiple output (MIMO) with up to 4 antennas. Research is now underway on 3GPP LTE-Advanced (LTE-A), which is a major enhancement to 3GPP LTE.
Closed subscriber group (CSG) services, which are services that can be provided only to a certain group of subscribers, have been introduced to improve quality of service. A base station (BS) capable of providing CSG services is referred to as a Home eNodeB (HNB), and a cell serving CSG members is referred to as a CSG cell. The basic requirements regarding CSG services are as disclosed in 3GPP TS 22.220 V1.0.1 (2008-December) “Service requirements for Home NodeBs and Home eNodeBs (Release 9)”.
Given that most CSG services are provided at higher costs than other typical wireless communication services, it is important to guarantee the quality of CSG services. There is a need for a method and apparatus to improve the quality of CSG services.